A. Field of the Invention
This invention relates generally to an improved refuse loader and more particularly to an apparatus for lifting, tilting, and emptying on-site trash containers into the access area for a compartment of a mobile collection vehicle.
Mobile collection systems for the picking up trash, refuse, or recyclable articles at numerous and separated sites are well known to the art. These systems consist of a vehicle traveling a standard route and standard containers designed to be automatically picked up on-site and dumped into the vehicle by an apparatus associated with the vehicle. These standard sized collection containers all have the same capacity but capacities differ from system to system, usually from approximately 50 to 300 gallons. In practice, the on-site containers are filled by the user and periodically the contents of the container are transferred to a mobile collection vehicle for transportation to a dump, land fill, or recycling center.
In order to provide a mechanism for efficiently emptying the on-site containers into the collection vehicle, various devices can be found in the prior art. These devices generally incorporate a vertical mast or boom which supports a means for grasping the container which is resting on a level surface, elevating the grasping means and grasped container to the top of the mast, dumping the container into an access opening in the top of the collection compartment, and returning the grasped container to its original position. Most of these devices also have a means for extending the vertical mast or boom a distance from the vehicle to accommodate the variable distance between the vehicle and the container.
B. Description of Prior Art
The prior art is replete with various devices for elevating and dumping the contents of a grasped container into a collection vehicle. These devices used to perform these two functions fall generally into two categories, those using chain drives and those using lever arms, either articulated or non-articulated.
U.S. Pat. No. 3,910,434, issued on Oct. 7, 1975, to Ebeling, is an example of the chain drive device. The invention employs a continuous linked chain driven by sprockets, or gears, mounted at the top and bottom of the mast, whereby the container grasping means, connected by links to the chain, and grasped container are carried to the top and then over a semicircular shaped mast head. The mast is connected by horizontal supports to the frame of the collection vehicle so that the entire apparatus can be extended away from the collection vehicle a short distance in order to provide more precise positioning to the container. A disadvantage of this device is that it has a large number of moving parts, so that the chains wear and frequently break from the stress of use.
The second type of device is illustrated by U.S. Pat. No. 4,427,333, issued on Jan. 24, 1984, to Ebeling, in which the chain drive mechanism is replaced with an articulated arm arrangement powered by a hydraulic cylinder and piston. A special linkage operating in conjunction with the articulated arm assembly and having four separate axes of rotation within its parts rotates an upper arm so as to swing the container grasping means and grasped container up along guide tracks to the top of the mast where the container was tipped and its contents dumped into a collection vehicle. From a pivot point at the top of the mast, the articulated arm lifts the container grasping means and grasped container the vertical distance of the mast. Like the chain drive device, the entire apparatus can be extended from the collection vehicle by various means mounted to the frame of the collection vehicle, whereby the device can be positioned more precisely with relation to the container. However, this device has several disadvantages as well. First, the height of the arms as they swing over the top of the collection vehicle can cause vertical clearance problems in tightly restricted areas. Second, the number of pieces comprising the linkage creates problems of manufacturability and cost. Third, the design itself tends to be heavy and cumbersome and does not lend itself to downsizing for smaller, residential loads which, because of their reduced weight and bulk, can be serviced with a lighter device having commensurate less expense to manufacture.
All such refuse loading devices share another common problem, namely, as the container grasping apparatus traverses over the top portion of the mast, more force is required to move the container grasping apparatus. For the linear portion of the mast, the force vector necessary to lift the apparatus only has a vertical component since it is overcoming gravity only. However, when the apparatus changes direction as it begins to traverse the curved portion of the mast, a horizontal component of force is required, so that the vector sum of the original vertical force component and the increasing horizontal force component is now greater in magnitude than the magnitude of the original force. Thus, more power is required as the apparatus traverses the curved portion of the mast.
The use of chains, pulleys, and cables employed in the elevation mechanism all increase the part count and thus provide more opportunity for failure of a part. A rack and pinion gear is commonly known in the mechanical arts, as for example in the steering mechanism of cars. Such rack and pinion arrangements can be used for lifting objects, as illustrated by U.S. Pat. No. 5,558,181, issued on Sep. 24, 1996, to Bundo. In this invention, an elevator is driven by a plurality of pinions carried on the elevator cage which engage a plurality of vertical racks secured to the sidewalls of the elevator passage. A primary feature of this device is the presence of a crown gear driven by a screw shaft connected to a motor mounted on the elevator cage, thus creating an irreversible driving device; this arrangement prevents the cage from falling in the event of a motor failure. However, this invention does not suggest or teach the use of a single rack and pinion for such purposes, and emphasizes the irreversible aspect to the invention as a safety device to provide passive braking.
What is needed therefore is an apparatus for elevating a trash container and inverting it over the elevated access area of a compartment that will accomplish the following objectives:
1. Reduced requirements for horizontal and vertical clearance so that it may be operated within narrow alleyways and driveways in residential areas;
2. Reduced number of parts to aid in manufacturability and reduce expense; and
3. Reduced number of moving parts to improve repairability.
4. Controlled traversal of the container grasping means as it traverses the curved part of the apparatus to reduce centrifugal force on the container and thus reduce strain on the apparatus.
It is therefore an object of the present invention to provide an improved apparatus for elevating a grasped container from a rest position on a level surface to an elevated position above the access area of a collection compartment and tipping the container so that the contents of the container falls by gravity into the access area.
Another object of the invention is to provide a method of controlling the speed of the container grasping apparatus as it traverses a curved portion of the elevating device which causes the container, along with the container grasping apparatus, to be inverted.
Another object of the invention is to provide a method of providing power to assist the container grasping apparatus as it traverses the curved portion of the elevating device which causes the container, along with the container grasping apparatus, to be inverted.
Another object of the invention is provide an improved means for mounting the invention to a trash collection vehicle.
Another object of the invention is to provide a means for mounting the invention to a trash collection vehicle in a location other than the under carriage so as to improve ground clearance for the vehicle which is so equipped.
Another object of the invention is to provide a trash elevation apparatus which has a reduced part count so as to aid in manufacturability, maintenance, and expense.
These objects of the invention are achieved by an apparatus consisting of an improved track assembly with a linear portion in a substantially vertical plane and with a curved portion at its upper end. The track assembly is supported by extendable, horizontal frame assembly at its upper end connected to the collection tank, and not connected at its lower end connected to the vehicle frame as heretofore. The improved track assembly supports and guides an improved carriage assembly having a self-contained motor which powers the carriage assembly vertically up and down the track assembly and arcuately over the curved top of the mast assembly. To assist movement of the carriage assembly over the curved portion of the track assembly and to control the speed at which the carriage moves over the curved portion, an improved dumping assembly is provided. It consists of a crank on one end of a rotatable tie bar for grasping trunions protruding from either side of the carriage assembly as the carriage assembly approaches the top of the vertical portion of the track assembly, and a piston connected to the opposing end of the tie bar through an arrangement of an articulated, pivotable yoke and offset mounts, whereby the carriage assembly is guided up and over the curved top portion of the track assembly by the crank, the container is upended, and its contents is dumped into the collection tank. The configuration of piston, yoke, and offset mount provides a unique means to, first, brake the momentum of the carriage assembly as it goes over the top of the track assembly and, second, to provide additional power to assist the movement of the carriage assembly as it transitions from a linear to an arcuate path. This configuration also does not extend beyond the confines of the track assembly and thus prevents clearance problems when the vehicle on which the apparatus is mounted travels through narrow streets and alleyways.
The method of moving the improved carriage assembly along the track assembly consists of a rack and pinion arrangement, whereby the rack extends the length of the mast and the pinion gear is mounted on the carriage assembly and self-powered by a motor within the carriage assembly. A pair of guide rails are provided on either side of the rack to hold the carriage assembly to the track assembly by means of wheels mounted on the carriage assembly and journeled into channels provided by the guide rails. This arrangement also maintains the pinion gear in close proximity to the rack so that the teeth of the rack and pinion mesh properly. The pinion gear also serves as a brake to prevent the carriage assembly from descending the track assembly when movement is arrested.
The vertical portion of the rack is a standard linear sheet of metal in which is stamped or formed a series of spaced ridges forming teeth. The curved rack portion of the rack consists of a unique arrangement of horizontal bars mounted between the guide rails and having the spacing which meshes the bars to the pinion gear. These bars allow the carriage to continue movement beyond the top portion of the track assembly and over the curved portion of the track assembly, by providing engagement points for the pinion gear in the carriage assembly. It is also believed that this arrangement aids manufacturability by removing the necessity of fabricating a curved rack portion from sheet metal which has a different spacing of teeth in the curved portion of the rack due to the rack""s curvature. An additional advantage of this bar arrangement is that debris cannot build up on the curved portion of the rack but will fall between the bars.
A container grasping apparatus which is standard to the industry and commonly used is connected to the carriage assembly and powered by hydraulic means.
The manner in which the frame assembly is moved transversely is considered to be a unique and innovative part of the invention. A double piston arrangement is used to achieve movement and is powered by the same hydraulic system used to power the carriage assembly, the gripping assembly, and the power assistance assembly. The double piston arrangement is used in lieu of previous chain and sprocket mechanisms and/or nested channel arrangements, so as to achieve a more dependable, less breakage prone mechanism.
The improved trash handling apparatus thus described is believed to be more compact and lightweight than similar devices described heretofore, and improves manufacturability of the apparatus because of its reduced parts count and simplicity of construction.